| Background Glucocorticoid(GC) is the key factor of the hypothalamus-hypop hysis-adrenal gland-immune axis. It not only takes part in regulating the immune homeostasis and inhibiting the over-activity of immune system, but also plays a very important role in the thrapy of autoimmune disease. Whereas, more and more evidence showed that GC-resistance was found in some tissue or organs under certain conditions, manifested different therapeutic responses in patients in clinic that gave a new challenge to the successful treatment of many autoimmune diseases including SLE. However, the molecular mechanism of the resistance to GC therapy is not still understood.Delineation of the molecular basis for GC resistance is critical for the development of new treatment apporches for this patients,and may provide new insights into the pathogenesis of autoimmune diseases. The pharmacologic action of GC are mediated through intracellular receptors, the glucocorticoid receptor(GR). There are two isoforms of GR in human cells, GRαand GRβ, which are generated from a single gene via alternative splicing of the primay RNA transcript. GRβcan't bind GC and does not transactivate GC sensitive genes. It functions as a dominant inhibitor of GRa.Several studied indicate that GC resistance has been associated with increased expression of GRβ.Recently it was reported that the member of serine/arginine-rich proteins SRp30c is necessary for alternative splicing of the GR pre-mRNA to creat mRNA encoding GRβ. And heterodimer fomation of GRα/Grβmay account for the reduced effectiveness of GC action in cells overexpressing GRβ.So upregulation of splicing factor SRp30c might stimulate the expression of GRβby alternative splicing in GC resistant patients.Objectives To clarify the relationship between the expression of human glucocorticoid receptor(GR)α,βsubtype and alternative splicing factor SRp30c in peripheral blood mononuclear cells (PBMC)of patients with Systemic lupus erythematosus(SLE) lupus nephritis(LN) and the clinic response to GC. To study the role of SRp30c in the splicing of GR pre-mRNA by observing the relationship between the expression of GRβand SRp30c.Analysis their relationship with clinical and laboratory parametersMethods Select 56 patients with SLE were enrolled into this study, which include the GC sensitive group (28 cases) and the GC resistant group (28 cases) from April 2005 to March 2006. and the 28 healthy adults as control. Patient were classified as GC-resistant or GC-sensitive based on responsing to prednisone, Semi-quantitative RT-PCR was performed to investigate the expression of GRα,GRβand SRp30c mRNA in SLE patients and healthy people,immunocytochemistry(ICC) was used to detect the protein of GRα,GRβin SLE patients and healthy people , in addition to, compare the expression of GRα,GRβand SRp30c in three groups . The clinical and laboratory parameters were also recorded.Results1. Level of GRαand GRβmRNA and SRp30c mRNA in PBMC were detected in three groups. and the expression of GRαis higher than GRβ; but the expression of GRαmRNA in the two groups of SLE was found no statistical significance compared to the normal(P>0.05) , The expression of GRβand SRp30c mRNA on PBMC in resistant group of patients with SLE was significantly higher than that in sensitive group and in normal controls (P<0.01). The ratio of the GRα/ GRβin resistant group is reduced compared with sensitive group and normal controls (P<0.05)2.The distribution and intensity of expression of GR subtype in the samples from the GC sensitive group, the GC resistant group and the normal control group were detected by immunocytochemistry SABC-AP method. The number of GRβpositive PBMC in resistant group was also significantly higher than that of sensitive group and normal controls (P<0.05); and also the ratio of the GRα/ GRβpositive PBMC is lower than sensitive group and normal controls (P<0.05)3.In the clincical and laboratory parameters, 24 hour urinary protein excretion and SLEDAI score as well as renal damage interval also showed significant differences between two patient groups(P<0.05), With the logistic regression advanced method, we found only the expression of GRβand sRP30c mRNA.were the independent risk factors for the GC- resistant .Conclusion The expression level of GR subtype and SRp30c mRNA is different in GC sensitve group and resistant group. Which indicated that there was GC-GR disorders in SLE patients, Taken together,our results suggest that formation of transcriptionally impaired GRα-GRβheterodimers is an important component of the mechanism responsible for the dominant negative of GRβ. lower GRβ,SRp30c mRNA related to better effect and higher GRβ,SRp30c mRNA related to GC resistance.1. This study suggested there did exist many GC resistant patients.2. The intensity and quantity of the GR subtype expression in the GC sensitive group, the GC resistant group and normal control group was different.3. The expression of GRβand SRp30c in the GC resistant group was increased compared with the GC sensitive group, indicating their negative correlation between the therapeutic effect of GC and the quantity of GRβ,SRp30c expression.4. These findings suggest that both GRβand SRp30c especially the ratio of GRα/GRβplay an important role in the mechanism of the action of GC,and GRβfunction as a dominant negative inhabitor of GRαin there.The expression of GRα,GRβand SRp 30c on PBMC in patients with SLE may serve as predictors of glucocorticoid response.
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